What is mono? they switched my medication to mucinex (guaifenesin) dm

Mono is a viral: illness, causing sore throat, swollen lymph nodes (glands) in the neck area and fatigue. It is caused by the Epstein Barr Virus. It can also cause some inflammation of the liver and spleen. I'm not sure what medication you were switched from, so can't answer the second part of your question. Please give us more info and one of us can respond again. Feel better!

Mononucleosis: Mononucleosis often called Mono is an infection caused by the Epstein-Barr virus. Sx fever, sore throat, fatigue, weakness, swollen glands in neck and armpits, loss of appetitie, night sweats. Usually spread by saliva hence kissing disease. Can be spread by exposure to cough sneeze, sharing food utensils. Develop sx after 4-6 weeks exposed to virus. monospot test. rx is supportive. no abx. rest

Mononucleosis: Mononucleosis is a viral infection (EBV) that can cause extreme fatigue, sore throat, cough, abdominal pains, headaches, swollen lymph nodes and other symptoms. Spleen enlargement is an uncommon but serious possibility. EBV is a lifelong infection, but usually remains silent. Viral shedding is at it's peak just before symptoms start and until fever resolves and you are not feeling as ill.